Process of purifying textile fabrications



@ATiON 0F IEXHLES & HBEHS,

PatentedNov. 18, 1924.

UNITED S PTENT OFFICE.

JOHN MARSDEN, OF NORTH DIGHTON, MASSACHUSETTS, ASSIGNOR TO MOUNT HOPE FINISHING COMPANY, OF NORTH DIGHTO'N, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

PROCESS OF PURIFYING TEXTILE FABRICATIONS.

No Drawing.

To all whom it may concern:

Be it known that I, JOHN MARSDEN, a subject of the King of Great Britain, residing at North Dighton, in the county of Bristol and State of Massachusetts, have invented certain new and useful Improvements in Processes of Purifying Textile Fabrications, of which the following is a specification.

This invention relates to the purification of textile fabrications, a term herein employed to include fibers or fabrics whether in the form of yarn or cloth, and comprises a process whereby this may be accomplished in amuch shorter time than that heretofore required, and likewise with an improved result as regards the texture and luster of the finished fibres, the effectiveness, uniformity and permanence of the bleach, and avoidance of that species of injury to the fibers known as tendering and due to the employment of oxidizing conditions of undue severity. The process is chiefly applicable to cotton goods, including not only raw cotton, but artificial silk and mixtures there of with cotton, as well as mercerized cotton;

It is well known to those skilled in this art that raw cotton, in common with all fibers of vegetable origin, is a highly comlex substance, having a basis of pure celulose but containing also a variety of com plex organic bodies of undetermined constitution and imperfectly understood chemical relations, these bodies comprising waxes, proteid bodies, pectic matters, coloring materials, and perhaps others, collectively known as the non-cellulose constituents. The essential problem involved in the purifying operation is the isolation of the cellulose without injury to itself, and this problem has been approached in the past in a great variety of ways, all of which have necessarily been largely empirical in character, since many of the fundamental constants of the chemical reactions involved have been and still are unknown.

It is known, however, that the organic non-cellulose constituents of the fiber are,

as a whole, less resistive to, or more readily attacked by oxidizing agents, than cellulose; and the present methods of isolating cellulose are based on the fundamental idea that the non-cellulose constituents, or most of them, can be selectively oxidized in pres- Serial 1W0. 600,453.

ence of the cellulose, leaving the latter in a pure or comparatively pure state. It is well recognized however that the differences between cellulose and its associated noncellulose bodies, as respects reactivity toward such powerful oxidizing agents as the hypochlorites for example, are not very great; and accordingly it is a matter of extreme practical difficulty to accomplish and industrially complete removal of the noncellulose without injury to the cellulose.

As will more fully appear hereinafter, I have discovered that by a suitable preliminary or conditioning treatment carried out at normal or only slightly higher temperatures, which temperatures should in no event attain the boiling point of water at atmospheric pressures, I am enabled to increase very greatly the reactivity toward the hypoclilorites of the non-cellulose constituents of the fiber, with the result that these non-cellulose constituents may in a subsequent oxidizing operation be quickly and readily destroyed or removed, leaving the cellulose unimpaired.

In order that the principles involved in my novel process may be clearly understood, I will explain 'that the process of purifying cotton goods, as now commonly practiced, involves the following steps:

(1 Singing to produce a clear face;

(2 Boiling from 8 to 10 hours at 10-40 lbs. pressure, in an alkaline liquor, for the purpose of dissolving and eliminating the natural impurities of the raw cotton as well as the sizing materials used in the fabrication of the cloth, (the so-called kierboiling) (3) A repetition of the above pressure boiling;

(4) Washing;

(5) Bleaching with sodium hypochlorite solution etc., (chemicking) (6) Washing;

(7) Souringg I (8) Washing;

(9) Drying, preparatory to the final dyeing and finishing operations.

According to my improved process I omit altogether the expensive kier-boiling or any high-temperature treatments, as well as the usual chemicking or bleaching operations; and I subject the gray product direct from the singeing frames to a cold conditioning operation, followed by a brief and carefully controlled subjection to gaseous chlorin, acting in the presence of an alkaline solution. Thereby I am enabled to shorten the total process from several days to a few hours, and furthermore to secure in full the dyeing qualities, and in part the lustrous appearance, now obtained only by the expensive step of mercerizing. If desired I may, by a slight modification of my process, attain the full mercerizing effect.

I have found that the reactivity of the organic non-cellulose components of the fiber is a function of the surface exposed to the oxidizing agent, which in the process about to be described is a hypochlorite at theinstant of its formation. Accordingly I subject the raw fibers to a conditioning treatment having for its purpose the extending to the maximum attainable degree of the exposed surfaces of the non-cellulose matters. This maximum extension of the exposed surfaces is preferably brought about by a treatment with cold dilute alkali or alkalinereacting salt (carbonate, hydroxid, phosphate, etc.) which has two functions, to wit, (1) to remove by solution a certain portion of the non-cellulose, thereby permitting freer access of the solution to the remainder, which is not capable of being dissolved under the operating conditions; and (2) swelling or distending the undissolved non-cellulose residue to increase its surface exposure and hence its reactivity. Following this conditioning treatment the fabrication is caused to take up a controlled proportion of alkali or alkaline-reacting salt and is at once subjected in swift movement to an atmosphere containing chlorin gas, either undiluted, or in case it is difficult or impracticable sutficiently to limit the time of exposure tothe gas, diluted by air, carbon dioxid or other relatively inert gas.

Following is an illustrative and preferred embodiment of my process as applied to the treatment of cotton cloth in open widths, it being understood that the invention is not limited to woven fabrics, nor to the precise conditions set forth by way of example, since in this as in most similar cases time, temperature and concentration are co-related factors in the sense that any one may be varied somewhat in conjunction with a cor responding variation of the others; moreover, the exact conditions to be used will depend somewhat upon the permeability of the material treated; for example in case of tightly woven fabrics with tightly twisted yarns, the alkali solution should preferably be of somewhat higher concentration, and the exposure tochlorin gas should be somewhat lengthened:

The cloth is thoroughly wetted out with a caustic solution of about 3 Tw, and the excess of solution squeezed out. After about four hours standing in the cold the cloth is washed free of alkali and soluble impurities. It is then again wetted with a solution of caustic soda of 3 Tw and is passed through an atmosphere of gaseous chlorin at a speed of about 60008000 yards per hour, the total time of exposure to the chlorin of any given area of the cloth being approximately l530 seconds. The preferred dimensions of the chlorin chamber are such that only about 40 yards of the cloth are exposed to the gas at any given instant, and chlorin is admitted to the chamber at a rate suflicient to maintain a constant concentration (pressure) therein. Immediately upon leaving the chamber the cloth is passed through a solution of soda ash of 4 Tw, this concentration being sufficient to neutralize the residual chlorin in the cloth, with a decided excess of the alkali. The cloth is then permitted to lie for a sufficient time, usually from 20 minutes to one hour, to accomplish a thorough by-bleach, after which it is washed out and finished in the usual way.

In case it is desired to mercerize the cloth, the mercerization is preferably carried out in known manner in connection with the first alkali treatment; or, alternatively, after the cloth has been subjected to our hypochlorite treatment.

It will be observed that my process does not involve at any point the kier-boiling or pressure digestion of the stock; and such boiling or digestion would defeat the objects which I seek to attain. By the omission of this boiling I not only secure an improved result as regards color and texture of the fabrication, but I save a considerable element of cost in fuel, and a very large element of cost in time.

I am aware that it has been proposed to subject cotton stock to the direct action of chlorin, either in presence or absence of alkali; but so far as I am aware such treatment has not before my invention been applied to a fabrication which has been properly conditioned to increase the reactivity of the non-cellulose constituents. In the absence of such proper conditioning the chlorin treatment will necessarily be ineffective, being either too mild to destroy or remove the non-cellulose bodies, or, if intense enough to accomplish this result it will act injuriously upon the cellulose. It is only by establishing a new differential between the reactivities toward the hypochlorite of the cellulose and the non-cellulose respectively, that the desired isolation of the former can be accomplished.

My invention is not limited to any particular type of apparatus, but it lends itself well to a continuous operation and is carried out continuously in practice. The preferred apparatus comprises a gas-chamber provided with means for efiecting the traverse of the cloth or yarn at the necessary rate, as by means of driven and idle rolls, and means for the controlled admission of the chlorin, in conjunction with deep seals at the inlet and outlet respectively. These seals may advantageously contain the alkali solutions employed as described above for the pretreatment and the after-treatment of the cloth.

I claim:

1. In a fiber-purifying operation, the steps comprising subjecting an unbleached fabrication to a cold conditioning operation serving to increase the reactivity of the non-cellulose components, and thereafter selectively.

oxidizing said non-cellulose components by means of a hypochlorite formed in presence of the fiber.

2. In a fiber-purifying operation, the steps comprising subjecting an unbleached fabrication to the action of an alkali at a temperature below the atmospheric boiling point, thereby increasing the reactivity of the non-cellulose components; washing to remove dissolved matters and again moistening with alkali; and then exposing the fabrication for a limited and controlled period to an atmosphere containing clilorin, whereby the non-cellulose components are selectively oxidized by means oi a hypochlorite formed in presence of the fiber.

In testimony whereof I aflix my signature.

JOHN MARSDEN. 

